Sound like there could be something broken on that gear fork set.

Watch the shifter cables at the tranny while someone shifts (car off) to see if the casings move (they shouldn't) and how far the levers move in 2,4,r. The hold downs may have gotten loose. Also if casings or shifter moves under the stick shifter itself. Otherwise you may have an internal tranny problem (usually worn bearings causing too much input/intermediate shaft end play). Or broken like spyderdrifter says.

Check the shifter cables. 2 and 4 are usually on the same push/pull. They may have gotten out of adjustment.